Refrigerator operated by a fluid fuel burner for a movable structure

ABSTRACT

Heat-operated refrigeration apparatus has heat dissipating members and a heat receiving part in a space defined in part by an exterior vertical wall of movable structure, such exterior wall having first and second openings. The heat receiving part has a flue extending therethrough, the inlet of which receives heated products of combustion from a fluid fuel burner. Ambient air passes into the space through the first wall opening, a part of which flows upwardly in the space to effect cooling of the heat dissipating members and another part of which provides combustion supporting air for the burner. Heated flue gases from the outlet of the flue, together with air effected to cool the heat dissipating members, is discharged exteriorly of the movable structure from the space through the second opening. A by-pass connection is provided around the flue between its inlet and outlet which prevents the burner flame from being extinguished due to an abnormally high difference in pressure of ambient air outside the movable structure at the first and second wall openings.

United States Patent [191 Kenneryd et al.

[ Nov. 13, 1973 [75] Inventors: Karl Giista Lennart Kenneryd,

Vallingby; Olov Tage Magnusson, Bromma, both of Sweden [73] Assignee: Aktiebolaget Electrolux, Stockholm,

Sweden 22 Filed: Apr. 25, 1972 21 Appl. No.: 247,418

Primary Examiner-William F. ODea Assistant Exam inerPeter D. Ferguson Attorney-Edmund A. Fenander [57] ABSTRACT Heat-operated refrigeration apparatus has heat dissipating members and a heat receiving part in a space defined in part by an exterior vertical wall of movable structure, such exterior wall having first and second openings. The heat receiving part has a flue extending therethrough, the inlet of which receives heated products of combustion from a fluid fuel burner. Ambient air passes into the space through the first wall opening, a part of which flows upwardly in the space to effect cooling of the heat dissipating members and another part of which provides combustion supporting air for the burner. Heated flue gases from the outlet of the flue, together with air effected to cool the heat dissipating members, is discharged exteriorly of the movable structure from the space through the second opening. A by-pass connection is provided around the flue between its inlet and outlet which prevents the burner flame from being extinguished due to an abnormally high difference in pressure of ambient air outside the movable structure at the first and second wall openings.

7 Claims, 3 Drawing Figures REFRIGERATOR OPERATED BY A FLUID FUEL BURNER FOR A MOVABLE STRUCTURE BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to heat-operated refrigeration apparatus which is air-cooled. When such refrigeration apparatus is employed in movable structure, such as a trailer, camper or boat, for example, the heat receiving part and heat dissipating members of the apparatus are disposed in a space defined in part by an exterior wall of the movable structure which is provided with two openings. One of the openings serves as an inlet for ambient air for cooling the heat dissipating members in the space and for supplying combustion supporting air to a fluid fuel burner which coacts with the lower end of a flue extending through the heat receiving part. Heated flue gases passing from the upper end of the flue, together with air in the space which has effected cooling of the heat dissipating members, is discharagd exteriorly of the movable structure through the other opening.

2. Description of the Prior Art When refrigeration apparatus operated by a fluid fuel burner is employed in movable structure, such as a trailer or camper or boat, for example, difficulty is often encountered to make certain that the fluid fuel burner will operate continuously and not be extinguished. This is especially true when the movable structure is moving from one place to another and occurs when the on a of ambient air outside the movable structure fluctuates sufficiently to produce a difference in pressure at the two openings at the exterior wall of the structure. When this difference in pressure is sufficiently great, the pressure differential is transmitted to the burner and causes the flame to become extinguished. This pressure differential at the two openings of the exterior wall of the movable structure is produced when a heavy wind prevails outside the structure, either when it is stationary or moving. Such a pressure differential often occurs when a movable structure, such as a trailer or camper, passes another vehicle at close range and is traveling in the opposite direction on a road or highway. This objectionable because, although the supply of fluid fuel will be shut off automatically when the burner flange is extinguished, the food stored in the refrigerator may spoil due to lack of refrigeration.

It has already been proposed to provide sealed combustion systems for operating a fluid fuel burner for movable structures. In systems of this kind a first conduit supplies all of the combustion supporting air to a fluid fuel burner at the inlet of a heating flue. The first conduit is connected to the flue inlet in airtight relation therewith. A second conduit is connected to the flue outlet in the same manner for discharging heated flue gases exteriorly of the movable structure. In such closed systems the first and second conduits are connected to a pair of openings at an exterior wall of the structure.

While improved operation has been obtained with closed systems of the kind referred to above, they are relatively expensive. This is so for the reason that the refrigerators are available in a variety of sizes and they are installed in trailers, campers and boats which also vary in size and are of different types. Hence, care must be exercised to employ the correct connections and fittings for each installation to provide a sealed combustion system.

SUMMARY OF THE INVENTION outer wall thereof heated flue gases from the flue outlet and the air effecting cooling of the heat dissipating members. We accomplish this by providing a by-pass connection between the inlet and outlet of the flue. The by-pass connection, which includes at its lower end a housing that envelopes the fluid fuel burner, extends alongside the outer casing of the heat receiving part and extends upward beyond the outlet of the flue. A conduit connects the upper outlet end of the flue and the by-pass connection at a region below its upper end.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a fragmentary rear perspective view of a heat-operated refrigerator and an outer wall of a movable structure adjacent thereto;

FIG. 2 is an enlarged exploded perspective view of parts shown in FIG. 1 to illustrate the construction more clearly; and

FIG. 3 is a fragmentary rear elevation view, partly broken away and in section, of parts shown in FIGS. 1 and 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, we have shown our invention in connection with a refrigerator 10 for a movable structure 9, such as a trailer, camper or boat, for example. The refrigerator 10 has a thermally insulated interior with a front access opening closed by a door 11 hinged to the front of the cabinet in any suitable manner (not shown). The refrigerator 10 is provided with a top 13 which serves as a work counter and is mounted on a support frame 8 fixed to the floor 12 of the movable structure.

The refrigerator 10 is adapted to be operated by heat-operated refrigeration apparatus 7 which may be an absorption refrigeration system of a uniform pressure type and like that described in U.S. Pat. No. 3,512,371 to Sven A. Gurt and Karl H. Lindstrom, granted May 19, 1970.

The refrigeration system comprises a plurality of parts which are interconnected in a well-known manner and include a cooling unit (not shown) arranged to effect cooling of the interior of the refrigerator, a liquid heat exchanger 22, an absorber vessel 23, an absorber 24, a condenser 26, a heat receiving part or vaporexpulsion unit 6 and a vapor supply line 25 connecting of the refrigerator 10 have not been shown, such connections being well-known and their illustration not being necessary for an understanding of our invention. The disclosure in the aforementioned Gurt et a] patent may be considered as being incorporated in this application, and, if desired, reference may be made thereto for a detailed description of the refrigeration system.

The liquid heat exchange 22, absorber vessel 23, absorber 24, condenser 26 and heat receiving part 6 are positioned in a vertically extending apparatus space at the rear wall 14 of the refrigerator 10. When the refrigerator is installed in a space in movable structure 9 having an exterior or outer wall 15, as shown in FIG. 1, the apparatus space 5 is at the immediate vicinity of such outer wall.

The exterior or outer wall 15 'of the movable structure 9 is provided with openings 16 and 18 at the upper and lower parts of the apparatus space 5. The openings 16 and 18 are covered with apertured wall sections 17 and 19 which are formed with louvers 17 and 19', respectively. The apertured wall section 17 serves as an air inlet through which ambient air flows from the exterior of the movable structure 9 into the lower part of the apparatus space 5.

The absorber vessel 23, absorber 24 and condenser 26 constitute heat dissipating or heat rejecting members of the refrigeration apparatus 7. The heat radiated from these heat rejecting members causes sufficient upward flow of part of the ambient air in the apparatus space S by natural draft to cool the refrigeration apparatus during operation.

Ambient air introduced into the apparatus space 5 through the apertured wall section 17 flows to the burner 21 to provide combustion supporting air therefor. Gaseous fuel is supplied to the burner from a suitable source of supply through a conduit 34 having one or more openings 36' therein through which primary air is drawn into the conduit and mixes with the gaseous fuel to provide a combustible gas mixture. Secondary air is supplied at the burner tip 21 at which region the burner flame is maintained, to provide a complete combustible gas mixture. In a well known manner (not shown) a thermal member 35 having a part 35' at the vicinity of the burner tip 21is provided to shut off the flow of gaseous fuel to the burner 21 when the burner flame is extinguished.

' The flame produced at the burner tip 21 projects into the lower end of the flue 28 of the heat receiving part 6. In this way the flue 28 is heated by the heated products of combustion of the burner flame which effects heating of the heat receiving part whereby the refrigeration system will function to promote cooling of the interior of the refrigerator. The heated flue gases flowing from the upper end of the flue, together with air in the upper part of the apparatus space 5 which has effected cooling of the heat rejecting members, is discharged from the apparatus space exteriorly of the movable structure 9 through the apertured wall section 19' which serves as an outlet for the air and flue gases.

In accordance with our invention, in order to prevent the burner flame from being extinguished when the pressure difference of ambient air outside the apertured'wall sections 17 and 19 becomes abnormally high, we provide a passageway which may be referred to as a by-pass connection and is in parallel with the flue 28 and has its opposite ends in communication with the upper and lower ends of the flue. As best seen in FIG. 3, the by-pass connection includes a shell 31 which is in communication with the lower end of the heating flue 28 and within which the burner 21 is disposed.

Below the heat receiving part 6 is provided a housing 42 which envelops the shell 31 and burner 21 disposed therein. As seen in FIG. 2, the housing 42 is movable toward and from the rear wall 14 of the refrigerator l0 and is formed with slots 43 and 44 which receive the conduit 34 for gaseous fuel and thermal member 35. As

seen in FIG. 3, the shell 31 is formed with openings 32 and 33 in a wall thereof through which the conduit 34 and thermal member 35 pass. The openings 32 and 33, together with the slots 44 and 43 of the housing 42 which are in alignment therewith, form apertured zones through which ambient air in the apparatus space 5 can flow into the burner shell 31, as indicated by the arrows 45 in FIG. 3, to provide combustion supporting air for the burner 21.

As best seen in FIG. 2, the burner shell 31 is provided with a hinged flap 38 which can be moved to cover and uncover an opening 37 in the shell. The housing 42 enveloping the shell 31 is formed with an enlarged opening 42 through which the flap 38 is accessible and can be moved to uncover the opening 37 to ignite the burner 21. The bottom of the burner shell 31 also is provided with a bottom opening 36. With this construction ambient air in the apparatus space 5 also can flow through the opening 42 in the housing 42 and the bottom opening 36 in the shell to provide combustion supporting air for the burner 21.

The passageway connecting the upper and lower ends of the heating flue 28 further includes a passageway 39 which extends upward from the housing 42 exteriorly of the casing 27 of the heat receiving part 6. As best seen in FIG. 2, one part of the passageway 39 is defined by an elongated upright member 39a which is U- shaped in horizontal section and a side wall 27a of the casing 27 over which the member 39a is positioned. The lower part of the upright member 39a is formed with a downward projecting section 39b which extends below the lower end of the heat receiving part 6. The section 39b is cut away at one side, as indicated at 39c in FIG. 2. With this construction, with the upright member 39a positioned against the side wall 27a of the casing 27, the housing 42 thereafter can be moved rearward in FIG. 2 so that a side wall of the housing can overlie the downwardly projecting section 39b of the member 39a.

The upright member 39a includes a horizontal section 39d which forms a hood overlying the top of the casing 27 and the upper end of the flue 28 projecting upward therefrom. From the horizontal section 39d the upright member 39a includes a four-sided section 39e, the upper open end 39fof which is above the upper end of the heating flue 28. It will now be understood that the passageway 39 connects the lower and upper ends of the heating flue 28 and extends above the upper end of the heating flue.

We have found that the cross-sectional area of the passageway 39 desirably should be at least twice the cross-sectional area of the flue 28. The horizontal section 39d is in communication with the passageway 39 at an opening 41 therebetween. A screen 46 is provided at the region of the opening 41 which offers some resis-v tance to flow of gaseous medium therethrough, The screen 46 serves as a gas permeable wall means which desirably has a cross-sectional area which is less than the cross-sectional area of the passageway 39. Further, the cross-sectional area of the screen 46 is greater than and is less than twice the cross-sectional area of the heating flue 28. In place of the screen 46 a gas permeable wall of labyrinth form may be employed at the opening 41.

When the burner 21 is operating normally the draft on the burner causes the flue gases to pass upward through the flue 28, transverse section 39d and upper part of the passageway 39. After mixing with air in the upper part of the apparatus space 5, the mixture of flue gases and air flows exteriorly of the mobile structure 9 through the apertured wall section 19. Such upward natural draft flow of flue gases takes place in flue 28 for the reason that the temperature of the flue gases is considerably higher than that of the ambient air surrounding the mobile structure 9.

However, when the pressure of the ambient air exteriorly of the mobile structure 9 is such that the difference in pressure of ambient air at the apertured wall sections 17 and 19 becomes abnormally high and a suddent vigorous air current is transmitted through the apertured wall section 19 to the upper open end 39f of the passageway 39 or through the lower apertured wall section 17 to the housing 42 at the lower end of the passageway 39, the full effect of such vigorous air current will be diverted from the upper and lower ends of the flue 28 to the passageway 39 and only affect the flow of heated gases in the flue to a minor extent.

When a negative pressure prevails in the housing 42, the products of combustion produced by the burner 21 tend to flow downward in the flue 28. When this downward flow becomes too strong the burner flame will be extinguished. The influence of a pressure change of this kind is effectively prevented by providing the passageway 39 becauseits flow area is greater than that of the flue 28. Only a small portion of the flow of air and products of combustion entering through the upper open end 39f of the passageway 39 will be diverted therefrom into the horizontal section 39d and upper end of the flue 28 and the main portion of such air and heated gases will flow downward through the passageway 39 into the housing 42 and pass outward therefrom through the opening 42.

When a negative pressure prevails at the apertured wall section 19 which is transmitted to the upper end of the passageway 39 the by-pass connection provided by the passageway will function in a similar manner so that the normal flow of the products of combustion in the flue 28 will not be disturbed to any significant extent.

In view of the foregoing it will now be understood that the shell 31, passageway 39 and hood 39d define passageway means within the apparatus space 5, the lower and upper ends of such passageway means being removed from the air inlet and outlet openings 16 and 18 in the exterior vertical wall and communicating with the inlet and outlet, respectively, of the flue 28. Further, the passageway means defined by the shell 31, passageway 39 and hood 39a' is imperforate between its upper and lower ends to provide a by-pass connection between the inlet and outlet of the flue 28 for move ment therein of gaseious fluid which is out of physical contact with gaseous fluid in the apparatus space 5.

We claim:

1. In a movable structure having a space defined at least in part by an exterior vertical wall provided with first and second openings,

a. heat-operated refrigeration apparatus which is aircooled and has heat dissipating members and heat receiving part disposed in the space,

b. said heat receiving part including a flue extending therethrough with an inlet at one level and an outlet at a higher level,

c. a fluid fuel burner which is disposed below the inlet of said flue and coacts therewith for discharging heated products of combustion upward through said flue,

d. the first wall opening serving to admit ambient air to the space for upward flow therein past said heat dissipating members to promote cooling thereof and for flow to said burner to provide combustion supporting air therefor,

e. the second wall opening serving to discharge air from the space exteriorly of the movable structure after passing said heat dissipating members and to discharge exteriorly of the movable structure heated flue gases from the outlet of said flue, and

vertically disposed passageway means within said space, said passageway means having its lower and upper ends removed from the first and second openings in the exterior vertical wall and communicating with the inlet and outlet, respectively, of said flue, and said passageway means between its lower and upper ends being imperforate to provide a bypass connection between the inlet and outlet of said flue for movement therein of gaseous fluid which is out of physical contact with gaseous fluid in the space.

2. Apparatus as set forth in claim 1 in which a. said heat receiving part has an outer casing, b

. said burner is disposed within a shell,

. a housing below said heat receiving part, said housing enveloping said burner and shell therefor,

d. said passageway means defining a vertically extending passageway exteriorly of the casing of said heat receiving part, said passageway being laterally offset from said flue and extending upward beyond the outlet of said flue,

. said housing below said heat receiving part forming the lower end of said passageway means, and

f. conduit means connecting the outlet of said flue and said passageway means at a region thereof below its upper end.

3. Apparatus as set forth in claim 1 in which the cross-sectional area of said passageway means is at least twice the cross-sectional area of said flue.

4. Apparatus as set forth in claim 2 in which said conduit means, at a region thereof between said flue and said passageway means, is provided with wall means gaseous allows gaseious medium to flow therethrough and offers some resistance to flow of the gaseous medium therethrough, said gas permeable wall means having a cross-sectional area greater than the crosssectional area of said flue.

5. Apparatus as set forth in claim 4 in which said gas permeable wall means comprises screening.

6. Apparatus as set forth in claim 2 in which the cross-sectional area of said conduit means is smaller than the cross-sectional area of said passageway means and in a range which is greater than and less than twice the cross-sectional area of said flue.

to pass therethrough to said burner and to provide a path of flow for combustion supporting air the space to the burner.

from

Patent No. 3,771,320 Dated November 13, 1973 InVentor(s) Karl Gusts Lennart Kenner'yd et a1.

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Title Page, left-hand column, I line 12, "5357/71" after "Sweden" should read 5352/71 Column l,- line 1 1+, after- "This" insert is 4 Column .2, line L "support" before "fi'ame" should I read supporting 7 Claim L column 6, line LL, before "medium "gaseous allows gaseious" should read which allows gaseous Signed a nd sealed this 1 th day of June 1971+.

(SEAL) Attest:

EDWARD M.FLET0HER,JR; c. MARSHALL DANN Attesting Officer vCommis ssioner of Patents FORM PO-105O (10-69) I sc -pc 0375-pg9 v i U.S. GOVERNMENT PRINTING OFFICE 2 I" "'!'334, 

1. In a movable structure having a space defined at least in part by an exterior vertical wall provided with first and second openings, a. heat-operated refrigeration apparatus which is aircooled and has heat dissipating members and heat receiving part disposed in the space, b. said heat receiving part including a flue extending therethrough with an inlet at one level and an outlet at a higher level, c. a fluid fuel burner which is disposed below the inlet of said flue and coacts therewith for discharging heated products of combustion upward through said flue, d. the first wall opening serving to admit ambient air to the space for upward flow therein past said heat dissipating members to promote cooling thereof and for flow to said burner to provide combustion supporting air therefor, e. the second wall opening serving to discharge air from the space exteriorly of the movable structure after passing said heat dissipating members and to discharge exteriorly of the movable structure heated flue gases from the outlet of said flue, and f. vertically disposed passageway means within said space, said passageway means having its lower and upper ends removed from the first and second openings in the extErior vertical wall and communicating with the inlet and outlet, respectively, of said flue, and said passageway means between its lower and upper ends being imperforate to provide a by-pass connection between the inlet and outlet of said flue for movement therein of gaseous fluid which is out of physical contact with gaseous fluid in the space.
 2. Apparatus as set forth in claim 1 in which a. said heat receiving part has an outer casing, b. said burner is disposed within a shell, c. a housing below said heat receiving part, said housing enveloping said burner and shell therefor, d. said passageway means defining a vertically extending passageway exteriorly of the casing of said heat receiving part, said passageway being laterally offset from said flue and extending upward beyond the outlet of said flue, e. said housing below said heat receiving part forming the lower end of said passageway means, and f. conduit means connecting the outlet of said flue and said passageway means at a region thereof below its upper end.
 3. Apparatus as set forth in claim 1 in which the cross-sectional area of said passageway means is at least twice the cross-sectional area of said flue.
 4. Apparatus as set forth in claim 2 in which said conduit means, at a region thereof between said flue and said passageway means, is provided with wall means gaseous allows gaseious medium to flow therethrough and offers some resistance to flow of the gaseous medium therethrough, said gas permeable wall means having a cross-sectional area greater than the cross-sectional area of said flue.
 5. Apparatus as set forth in claim 4 in which said gas permeable wall means comprises screening.
 6. Apparatus as set forth in claim 2 in which the cross-sectional area of said conduit means is smaller than the cross-sectional area of said passageway means and in a range which is greater than and less than twice the cross-sectional area of said flue.
 7. Apparatus as set forth in claim 2 which includes a. piping for conducting combustible fuel to said burner, and b. said housing being apertured to enable said piping to pass therethrough to said burner and to provide a path of flow for combustion supporting air from the space to the burner. 